Conventional lighting systems often include light-emitting diodes (“LEDs”) capable of efficiently producing high-intensity, high-quality light. Mobile phones, personal digital assistants, monitors, displays, digital cameras, lamps, and refrigerator lights often have solid state lighting systems with LEDs. A group of different color LEDs can be used to produce a combined radiation emission. For example, a white light-emitting LED device (“white LED device”) can be a white RGB LED device that includes a red light-emitting LED (“red LED”), a green light-emitting LED (“green LED”), and a blue light-emitting LED (“blue LED”) that produce radiation emissions in the red region, green region, and blue region of the spectrum to make white mixed light.
Although LEDs produce less heat than many conventional lighting devices, LEDs can produce enough heat to cause a color shift (e.g., a shift of a peak emission wavelength) because the performance of light producing junctions can be highly temperature dependent. Fluorescent materials of light producing junctions also tend to deteriorate over long periods of time. It is difficult to compensate for changes in color coordinates due to color shifts and LED deterioration. White RGB LED devices often produce mixed light that appears off-white or yellow, which reduces the color fidelity of electronic devices.
Conventional lighting systems often include a temperature sensor used to monitor the junction temperatures of LEDs to compensate for peak emission wavelength shifts caused by temperature changes. To control the color coordinate of white mixed light, auxiliary red LEDs are used to increase the intensity of emitted red light to bring the combined radiation emission toward a target radiation emission to adjust the color rendering index (“CRI”). Unfortunately, auxiliary red LEDs occupy space on the LED mounting board resulting in a reduced number of sets of RGB LEDs.
Existing lighting systems have RGB sensors with three separate sensors, including a red sensor, a green sensor, and a blue sensor. These sensors are positioned in the luminaire to measure the individual light intensities of the red LED, green LED, and blue LED, respectively, in order to individually adjust the drive current to each LED to control the color coordinate of the mixed light. Temperature sensors, auxiliary red LEDs, and RGB sensors lead to increased manufacturing costs and complexity as well as increased energy consumption. Additionally, if these components occupy reflective space on the LED mounting board, the performance of the light/system can be reduced.